Flow curves of pure Bi or Bi-10Sn obtained by rotational viscometer

Abstract

Viscosity of pure Bi and Bi-10Sn molten alloy were measured in a low shear rate range. The flow curves of pure Bi and Bi-10Sn alloys were prepared from the torque data obtained by rotational viscometer, and the interaction between these metals and copper contact interface was investigated. When graphite cone was used, the viscosity of pure Bi was 3.29 mPa∙s and of Bi-10Sn was 86.7 mPa∙s. In the other hand, in case of copper cone, the viscosity of pure Bi was 5.65 mPa∙s and that of Bi-10Sn was 278 mPa∙s. It was considered that, in the range, the flow characteristics of pure Bi was Newtonian fluid and that of Bi-10Sn alloy was Non-Newtonian fluid. The surface adhesion was observed by XRD and EPMA analysis. Chemical interaction between Cu and Sn was confirmed from analysis results. Sorosite(Cu(Sn,Sb)) peak pattern was obtained for the pure copper cone after Bi-10 Sn viscosity measurement by XRD. The sorosite peak pattern was identified with a reaction product of Cu_1+x(Sn,Bi), and Bi atoms were substituted for Sb atoms in the sorosite. Reaction products Cu₃Sn was not detected by XRD. Cu₆Sn₅ peak pattern was observed in the XRD patterns obtained from an adhesive on pure copper cone near the edge. Bismuth atoms were removed from a sorosite ; Cu_1+x(Sn,Bi) (0.1<x<0.2) then the composition of Cu₆Sn₅ was derived.